Wide range investigations of essential oils useful in the control of the phytophagous insects have demonstrated an enormous progress in the field. Their actions could be attributed to the interference with metabolic, biochemical, physiological, and behavioral functions of insects. Earlier evaluations have established their activity as ovicides, fumigants, and contact toxicants. Some essential oils exhibit acute toxicity, whereas other are attractive or repellents, antifeedants or affect on growth and development or reproduction. In the last ten years, great advances have been made in laboratory and field studies about use of the essential oils for the control of many insect pests. Activity, mechanism of action and useful formulations are discussed for the following insect orders: Diptera, Lepidoptera, Coleoptera, Orthoptera, Isoptera, Hymenoptera and Homoptera. In particular, the problems related to the volatility of the oils and their poor solubility in water have discussed for an optimal application in field.